The effects of alcohol and dosage-set on risk-seeking behavior in groups and individuals.

A great deal of risky activity occurs in social contexts, yet only recently have studies begun to examine the impact of drinking on risk-seeking behavior in groups. The present study sought to extend this work by examining both pharmacological and expectancy (dosage-set) effects of drinking. In addition, by using a much larger sample than in prior studies we aimed to increase the power to examine how drinking affects the decision-making process (i.e., Does the initial proposed decision stand, or does it shift during discussion to a safer or riskier final decision?). Seven hundred twenty unacquainted social drinkers (half female) were randomly assigned to three-person groups that consumed alcohol (0.82 g/kg males; 0.74 g/kg females), a placebo, or a no-alcohol control beverage. After drinking, participants decided whether to complete a 30-min questionnaire battery (the less risky choice) or toss a coin and, pending the outcome of that toss, complete either no questionnaires or a 60-min battery (the riskier choice). Neither drinking nor believing one had been drinking affected the decision to toss the coin when participants deliberated in isolation. In contrast, when the decision occurred in a group context, groups led to believe they were drinking alcohol (i.e., groups administered alcohol or placebo beverages) were significantly more likely than groups knowing they had consumed a nonalcoholic beverage (i.e., groups administered a no-alcohol control beverage) to choose the coin toss. Results extend prior findings highlighting the effects of alcohol dosage-set in social contexts.